1、 Recommendation ITU-R SA.2044(12/2013)Protection criteria for non-GSO data collection platforms in the band 401-403 MHzSA SeriesSpace applications and meteorologyii Rec. ITU-R SA.2044 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical us
2、e of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World an
3、d Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for th
4、e submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of I
5、TU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination
6、, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite n
7、ews gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2014 ITU 2014 All rights reserved. No part of this publication
8、may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R SA.2044 1 RECOMMENDATION ITU-R SA.2044 Protection criteria for non-GSO data collection platforms in the band 401-403 MHz (Questions ITU-R 139/7 and ITU-R 141/7) (2013) Scope This Recommendation provides informa
9、tion on the current and future usage of the non-GSO data collection systems (DCS) in the 401-403 MHz, and the portioning of the band to allow all DCS systems equal access to the spectrum. The ITU Radiocommunication Assembly, considering a) that system designers require performance objectives in the
10、presence of interference for their systems; b) that performance objectives for representative systems operating in the EESS and MetSat services are intended to provide guidelines for the development of actual systems; c) that performance objectives for EESS and MetSat services are a prerequisite for
11、 conducting interference assessments; d) that protection criteria are required to meet the desirable performance objectives in the presence of interference, recommends 1 that the analysis to determine the effect on non-GSO DCS systems in the 401-403 MHz should be based on the following protection cr
12、iteria: 197.9 dB(W/(m2 Hz) maximum aggregate acceptable spectral power flux-density (spfd) at the antenna of a non-GSO DCS instrument for broadband noise interference (see Annex 1); 165.4 dB(W/m2) maximum power flux-density (pfd) within a resolution bandwidth of 19 Hz at the antenna of a non-GSO DCS
13、 instrument for each narrow-band spectral line interference (see Annex 2); 2 that protection criteria defined in recommends 1 should not be exceeded for more than a percentage of 1% of time in the field of view of the satellite. 2 Rec. ITU-R SA.2044 Annex 1 Protection criteria for non-GSO DCS instru
14、ments in the band 401-401.69 MHz against broadband noise interference emissions 1 Introduction This Annex provides information relating to an existing typical non-GSO DCS system in operation so called ARGOS and therefore to its protection requirements from broadband noise interference emissions. 2 S
15、pectral power flux-density threshold level of interference The addition of broadband noise to the ARGOS instrument will have the effect of increasing the system bit-error ratio (BER), and therefore adversely affect its performance requirement. This analysis identifies the maximum acceptable pfd asso
16、ciated with broadband noise in the ARGOS uplink channel. Figure 1 shows the main hardware elements on board the NOAA satellites. This general principle is applicable to METOP and NOAA satellites. FIGURE 1 On-board hardware equipment SA.2044-01ABAttenuation: 1.6 dB A-DCSA-DCS/SARP receive antenna (UD
17、A)pfdThe UDA antenna gain pattern specification is expressed according to the nadir angle in Table 1: TABLE 1 SARP/ARGOS receive antenna (UDA) gain pattern Nadir satellite angle 62 59 54 47 39 31 22 13 5 0 Gain in RHCP 3.85 3.54 2.62 1.24 0.17 1.33 2.24 3.08 3.80 3.96 Gain in LHCP 5.69 6.23 7.52 9.3
18、9 11.39 13.12 14.52 15.77 17.17 18.00 Axial ratio 6.02 5.85 5.59 5.26 4.90 4.57 4.31 4.11 3.78 3.49 The specified figures in Table 1 are of the receive antenna pattern shared between the SARP and ARGOS instruments, as they should be for the NOAA and METOP satellites. The ARGOS typical figures are: n
19、oise figure = 3 dB (ARGOS input parameter), worst-case background noise temperature = 1 200 K (measured value taking into account the industrial noise in Rec. ITU-R SA.2044 3 Europe), attenuation between the antenna and the ARGOS receiver = 1.6 dB. Thus, the system noise temperature at the input of
20、the ARGOS receiver (point B on Fig. 1) equals 1 214 K and therefore, the noise spectral density equals N0= 197.8 dB(W/Hz). The worst-case specification states that the ARGOS is designed to operate correctly when the received signal has a power C = 160 dBW (minimum level of the received signal) at th
21、e input of the receiver, which provides an effective Eb/N0= 8.3 dB in the bit detector of the ARGOS if we take into account the beacon waveform and the various losses. Therefore, in order to achieve a BER of 2 104that corresponds to a minimum Eb/N0of 8 dB, the maximum acceptable degradation is 0.3 d
22、B. Hereunder, the additive noise corresponding to the 0.3 dB degradation for the C/N0is calculated. Let I0represent the additive noise power density. Therefore, the initial N0noise becomes N0+ I0. The signal-to-noise ratio C/N0becomes C/(N0+ I0). The degradation is 0.3 dB = 10 log (C/N0)/(C/(N0+ I0)
23、, thus I0 /N0= 11.5 dB and I0= 209.3 dB(W/Hz) which corresponds to a temperature of 86 K, and therefore an increase of 7% of the system noise temperature at the input of the receiver. Therefore, the maximum admissible level of noise density is I0= 209.3 dB(W/Hz) (calculated for point B in Fig. 1). A
24、s shown in Fig. 1, the noise density, I0, takes into account the attenuation and the antenna gain. As the spfd is required, it is necessary to transform this figure in dB(W/(m2 Hz). The equivalent surface area of an antenna having a gain G is =42GS . Therefore, the corresponding spfd equals 209.3 +
25、1.6 (losses) 10 log10S = 197.9 dB(W/(m2 Hz), taking into account the highest satellite nadir angle. Annex 2 Protection criteria for non-GSO DCS instruments in the band 401-401.69 MHz against narrow-band spectral line interference emissions 1 Introduction This Annex provides information relating to a
26、n existing typical non-GSO DCS system in operation so called ARGOS and therefore to its protection requirements against narrow-band spectral line interference emissions. 2 Background Annex 1 contains the protection criteria for ARGOS in the band 401-401.69 MHz to be used as a basis for analysis of i
27、nterference from broadband interference emissions. This Annex provides protection requirements for the ARGOS instrument in respect of interference from narrow-band spectral line interference emissions. 4 Rec. ITU-R SA.2044 3 Protection requirement from narrow-band spectral line emissions Figure 1 sh
28、ows the main ARGOS hardware elements. To better understand the rationale of this specification, it is necessary to briefly recall the behaviour of the instrument. ARGOS beacon transmissions begin with 160 ms of unmodulated carrier to allow a phase-locked loop to lock more easily on the carrier. Figu
29、re 2 represents the ARGOS message format. FIGURE 2 DCS message format SA.2044-02160 ms carrier Synchronization bitsDCS beaconmessage content bitsA spectrum analyser in the instrument continuously monitors the full coverage bandwidth in search of the pure carrier portion of the DCS messages. When the
30、 spectrum analyser detects such a line, it considers that it is the beginning of a DCS message. The theory is based on the detection of a pure carrier wave (sine wave) in a white, additive and Gaussian noise environment. The power spectral density of the received signal (pure carrier + noise) is com
31、puted using fast Fourier transform techniques, and each signal above the system threshold is processed as if it were a DCS beacon (see Fig. 3). FIGURE 3 Detection of a sine wave in white Gaussian noise SA.2044-03f Detected peaksThreshold Power spectral densityThe ARGOS receiver processors are theref
32、ore designed to detect discrete spectral components (unmodulated beacon carrier) and the corresponding resolution bandwidth is 19 Hz. Signals above the threshold level are assigned to an on-board data recovery unit (DRU) for further processing and transmission to the Earth on the mission telemetry c
33、hannel. In order to satisfy ARGOS detection probability performances for a wide range of user applications (wild animal tracking, fishery, oceanography, etc.), the ARGOS instrument has been designed to detect and process extremely weak signals. Its performance is such that any signal, Cmin, which ex
34、ceeds the local noise density level by 21 dB(Hz) (Cmin/ N0 21 dB(Hz) would be assigned to a DRU for additional processing. Consequently, narrow-band interfering signals meeting this criteria would cause a DRU to be assigned to it. The consequence would be that the performance of the ARGOS instrument
35、, in terms of capacity (e.g. the number of simultaneous DCS messages that are able to be processed), would be seriously degraded. Rec. ITU-R SA.2044 5 The ARGOS typical figures are: noise factor = 3 dB (ARGOS typical figure), worst-case background noise temperature = 1 200 K (ARGOS input parameter),
36、 attenuation between the antenna and the receiver = 1.6 dB. Thus, the system noise temperature at the input of the receiver (point B on Fig. 1) equals 1 214 K and therefore, the noise spectral density equals N0= 197.8 dB(W/Hz). As Cmin/ N0= 21 dB(Hz), Cmin= 176.8 dBW. Therefore, any narrow-band spur
37、ious emission greater than 176.8 dBW at the input of the ARGOS (point B of Fig. 1), would result in a degradation of the system capacity. It is then necessary to compute this maximum admissible level of spectral line at the input of the ARGOS antenna. The ARGOS receive antenna gain pattern specifica
38、tion is expressed according to the nadir angle in Table 2. TABLE 2 Receive antenna (UDA) gain pattern Nadir satellite angle 62 59 54 47 39 31 22 13 5 0 Gain in RHCP 3.85 3.54 2.62 1.24 0.17 1.33 2.24 3.08 3.80 3.96 Gain in LHCP 5.69 6.23 7.52 9.39 11.39 13.12 14.52 15.77 17.17 18.00 Axial ratio 6.02
39、 5.85 5.59 5.26 4.90 4.57 4.31 4.11 3.78 3.49 Therefore, the maximum admissible power at point A of Fig. 1 equals 176.8 + 1.6 (losses) = 175.2 dBW, taking into account the highest satellite nadir angle. As the pfd is required, it is necessary to transform this figure in dB(W/m2). The equivalent surf
40、ace area of an antenna having a gain G is =42GS corresponding to the highest satellite nadir angle. Therefore, the corresponding pfd equals 175.2 10 log10S = 165.4 dB(W/m2). 4 Conclusion Following the above computations, the conclusions and recommendations regarding the impact of the aggregation of spectral narrow-band interference emissions, should not exceed 165.4 dB(W/m2) at the input of the ARGOS antenna for the frequency band 401-401.69 MHz, within a resolution bandwidth of 19 Hz. _
